The use of photocatalysis to prepare metallized semiconductor powders, such as TiO.sub.2 powder metallized with copper, is described in U.S. Pat. No. 4,264,421. These catalysts have utility, for example, in the photocatalytic decarboxylation of saturated carboxylic acid. Metallizing of the semiconductor powder is disclosed as being achieved with illumination from a 2500 Watt Hg--Xe lamp operated at 1600 Watts for less than about four hours.
Such a method for the decarboxylation of saturated carboxylic acids on n-type semiconductor powders (e.g., TiO.sub.2) is described in a companion patent, U.S. Pat. No. 4,303,486. The major reaction products are the corresponding alkanes and CO.sub.2. A suspension of the catalyst in a solution containing the acid is irradiated at ambient temperature. The reaction mixture can be subjected to irradiation in the presence or absence of oxygen and the semiconductor powder, such as TiO.sub.2, can be platinized.
Lastly, in Netherlands Pat. No. 7,013,639 there is disclosed the oxidation of hydrocarbons, such as isobutane, in gaseous or vapor phase, said hydrocarbon being passed, admixed with oxygen and at a temperature of not more than 100.degree. C., over a metal oxide catalyst such as TiO.sub.2 irradiated with UV light, to produce acetone.
Despite the teachings of the art, there has not been a recognition of the use of specific semiconductor powders for the selective oxidation of olefins, by photochemically activating a suspension of the semiconductor powder, the olefin and a suitable solvent.